On another thread, it almost got off topic by virtue of talking about shtf milsurp rifles. The very idea of such a thing dictates that you also add "inexpensive" in the criteria. So here is the thread on inexpensive shtf milsurp rifles. My choice, hands down, is the SKS; cheap (well, it used to be), rugged and cheap to run. They can be used as a club or spear, if the situation arises. Spare parts are available. Minimum round capacity is 10 and it can go upward from there. They do occasionally go off on their own, but that just adds to their intimidation factor.
If "inexpensive" is the deciding factor I would also lean towards the SKS platform for a semi-auto due to the relatively inexpensive cost of the rifle and fact that ammo is cheap, plentiful, and easy to stock up on. For a bolt action, I would go with a Mosin (probably a M44 due to it's compact size and folding bayonet) for the same reasons. If cost was no issue, I would probably pick a quality milsurp AK over any other semi-auto. On the bolt action side I would go with a SMLE (probably No 4 MK II) due to the quick, cock on close bolt system, and 10 round capacity. The other possibility (if you could locate one) would be a 1903 with a 25 round air service magazine installed. The only issue with both the 1903 and Lee Enfield is that the cost of ammo is so expensive that I would not likely have a large quantity of ammo on hand for each rifle.
As pointed out in the other thread, the Moisin Nagant would be a very valid choice as well. It is stil fairly inexpensive. Luke mentioned the SMLE. The Ishapore has the same bolt system and it uses 7.62 NATO ammunition. It is a good, strong rifle to boot.
SKS is pretty much the standard SHTF fall back gun. Even though it only holds ten rounds, it can be topped off pretty quick. Another often overlooked is the M1 Carbine. Easy to shoot, light, spare magazines are everywhere, ammo isn't the cheapest, but its not the most expensive. Bolt action would be my SC1903A3.
I would say SKS for semi auto because of the price and ammo. for bolt action i would say Mosin 91/31. I would hate to have a M44 because of the fact that *Its loud *Muzzle Flash *You might have to shoot alot and it may be difficult with the recoil. if price was not an issue i would go with an AK for semi auto. For bolt action i would choose the De Lisle Silent Carbine because its quite, has low recoil, ammo is plentiful, and takes magazines (i think 1911)
For me it would hand down be an AK variant. I'm not even that picky about which variant as long as it had a folding stock. Ammo and mags are everywhere and cheap. So when the zombies attack, head to Walmart for 7.62x39 and some Twinkies.
I also like the M1 carbine. It would be my choice except for initial price and ammo price. I once had a National Ordnance M1 carbine with folding wire stock. Would have been an excellent choice. "Once had"! I seem to use that phrase a lot.
If the zombies attack you're SOL. Only thing left at wal mart will be snow balls. It's been proven inevitable.
Oh and I'd do an AK. SKS would be fine too but mag changes are just a hassle if you do the 30rd mags. Plus these days, at least on OSA and at fun shows, a cheap AK isn't that much more expensive than a cheap SKS for some reason.